The infestation of animals with parasites is highly undesirable. Companion animals, for example, horses, dogs and cats all can serve as hosts for a large number of internal and external parasites. In companion animals, the presence of parasites can lead to discomfort, impaired health and performance, and even death. Each year, for example, millions of dogs and cats in the United States are treated for fleas, ticks, and mites. Flea, tick, and mite infestations cause great discomfort, transmit disease to pets and humans, and significantly interfere with the relationship between people and their pets. Societal changes have brought pets into the family home, intensifying the need for disease prevention.
Several classes of insecticides are effective for combating parasites. For example, pyrethroids, organophosphates, and organocarbamates are used to treat animals for parasite infestation. Various methods of formulating anti-parasitic agents are known in the art. These formulations include oral treatments, dietary supplements, powders, sprays, topical treatments (e.g., dips and pour ons), and shampoos. While each of these formulations has some efficacy in combating parasites, the formulations generally include synthetic insecticides. Synthetic insecticides, although effective, have been known to cause environmental effects that are harmful to humans and to the companion animal. Similarly, Pyrethrin, although extracted from the Chrysanthemum flower, is hard to process and standardize.
Natural insecticides, i.e., insecticides that include natural plant essential oils as an active ingredient, have been known to kill household parasites such as ants, cockroaches, and fleas by applying the natural insecticide in the form of a spray, powder, or liquid to a locus or area to be protected from the parasites, as disclosed in U.S. Pat. Nos. 5,439,690, 5,693,344, 6,114,384, and 6,531,163. In particular, the natural active ingredient in the insecticide has been included at a concentration of approximately 0.1% to 10% by weight of the insecticide. As such, a need still exists for methods and compositions to kill parasites on companion animals that include natural plant essential oils, have the same or higher efficacy level than synthetic insecticides, while still not harming or irritating the companion animal or its owner.